1. Field of the Invention
This invention relates to a method for producing electrolyte solvents, and more particularly, this invention relates to an industrial scale method for producing electrolyte solvents.
2. Background of the Invention
The market for high power and high energy batteries continues to increase. However, the R&D for developing industrially scalable protocols is a barrier for many market participants.
Electrolytes are integral portions of batteries in that they shuttle charge to and from electrodes. A homogeneously mixed, well dispersed electrolyte facilitates efficient battery operation. Electrolyte solvents facilitate this homogeneity.
State of the art technology for preparing these solvents uses highly inefficient, multi-stage procedures requiring highly corrosive reagents. Further, a by-product is generated that requires additional processes to remove. Specifically, current methods for producing electrolyte solvents for lithium ion batteries require large amounts of flammable and peroxide-forming tetrahydrofuran (THF). (See Equation 1, below.) As a result, these methods use relatively large amounts of solvent for the reaction and workup to remove triethylammonium chloride byproduct. As such, time consuming, and multiple aqueous extractions of the product are necessary.
In Equation 1, 2-(2-methoxyethoxy)ethanol (molecular weight: 120.15 grams/mole) reacts with trimethylsilyl chloride in the presence of triethylamine and tetrahydrofuran to produce 2,2-dimethyl-3,6,9-trioxa-2-siladecane (molecular weight: 192.33 grams/mole) and triethylamine hydrochloride salt. The molecular structure of the reagents and products of Equation 1 can be seen in prior art FIG. 1.
Furthermore, state of the art methods require reaction times of more than 17 hours, which is not acceptable for scale-up protocols. For example, double distillations are necessary to achieve the electrolyte purity (approximately 99.5 percent) required by battery manufacturers.
Also, these methods require anhydrous solvents and reagents. These reactants need to be handled under inert atmospheres and protected from moisture.
Overall, state of the art processes generate large amounts of waste which need to be specially handled. Therefore, these processes are not economic.
A need exists in the art for a method for producing electrolyte solvent that allows its industrial scalability. The method should use nonproprietary reactants. The method should be run at relatively lower temperatures. Finally, the method should not require special atmospheres or handling.